Can Cross Training On A Bike Translate To Better Running Performance?

Picture from Bikatadventures.com

I had shin stress fractures in both legs from running too much when I was 20. The doctor I saw said that I could not run for a minimum of 6 weeks. I could only swim or bike. It was this cross training regime that got me started in triathlon later.

This concept cross training emerged in the 1980s along with the popularity of triathlon. Earlier studies reported that performance in a primary sport can be maintained despite reductions in volume of the primary sport by training in a variety of sports. These findings suggest potential crossover effects between endurance training modalities. Are these findings still relevant?

The following systematic review by Menges et al (2026) compared the effects of running only and cycling only training interventions to evaluate cross training transfer to sport specific VO2 max and running performance.

The authors found 7 studies with intervention durations of at least 4 weeks. These were run only training with cycling only or combined running-cycling interventions. Outcomes included VO2 max assessed on a treadmill or cycle ergometer as well as running time trial performance for 1 mile, 3000m and 5000m.

So does cross training on a bike help running performance? This meta-analysis suggests it does. The subjects who performed run only, bike only or combined running and cycling training performed similarly in the 1 mile, 3000m and 5000m time trials. They also had improved VO2 max values regardless of testing method (treadmill or cycle ergometer).

Cycling engages the quadriceps and gluteus maximus muscles in ways that running does not. When the muscles get stronger, it helps improve running economy and power (especially in hilly races).

Instead of running twice a day, you can take away some of the extra strain on the legs by cycling (or even training on the elliptical machine) without the repetitive impact forces of running. This is especially beneficial during recovery periods or for runners prone to injuries.

Cycling is low impact which is great for your joints. However, it does little to help your bone density. Running on the other hand has impact loading that helps to maintain or even increase bone strength which is great for older athletes.

The findings should be interpreted with some caution since there were limited studies (7) and the fairly short training period.

For shorter distances up to 5 km at least, there may not be any differences but in a longer event like the marathon, you still need to run since the run muscles will not used as much while cycling. Biking can definitely help the aerobic fitness but not the specific leg muscles, and running performance may decline.

Running and cycling can actively enhance each other when integrated carefully. If you're a runner looking to improve your endurance without extra impact or a cyclist looking for stronger stabilizing muscles, cross training helps.

The key is balancing both to meet your specific training goals while avoiding overuse injuries.

The principle of specificity suggests that cross training can offer general fitness benefits, the most significant performances are achieved through sport specific training. Before Sabastian Sawe broke the 2 hour barrier for the marathon, he was running in excess of 200 km a week in the 6 weeks leading up to London, with a maximum of 241 km (150 miles). 

So, runners and cyclists should incorporate cross training as a supplementary activity rather than a replacement for their primary sport.

References

Menges T, Dindorf C, Dully J et al (2026). Cross-Training Between Rnning And Cycling: Effects On VO2 Max And Running Performance- A Systematic Review And Meta-Analysis. Front Sp Act Living. 8: 1843803. DOI: 10,3389/fspor.2026.1843803

Tanaka H. (1994). Effects Of Cross-Training. Sports Med. 18: 330-339. DOI: 10.2165/00007256-199418050-00005

Carbon Plated Shoes And Stress Fractures

Picture from Prodirectsport

I just saw 3 different people wearing carbon plated shoes at the Cold Storage in Holland Village. They were shopping for groceries and definitely not running. On one hand you have someone like me who's still unwilling to run in carbon plated shoes while on the other hand they are a dime a dozen amongst runners now (and people walking in Cold Storage). Most runners use them in training as well, not just at races. 

No running study has studied whether carbon plated shoes (known as advanced footwear technology or AFT) changes running biomechanics associated with bone stress injuries (BSI), or shin splints. The researchers goals were to measure running biomechanics while running in an AFT shoe.

23 runners (11 women, 12 men) with an average age of 25.4 ± 2.7 years were recruited for the study. They ran randomly in 3 different types of running shoes, neutral, lightweight (responsive foam) and AFT at 3 self selected running speeds. A run at their 'training effort', a tempo run and at 5 km race pace.

Biomechanical variables associated with BSI such as cadence, vertical ground reaction forces, ankle and rearfoot eversion forces were measured during each run and shoe condition.

Results show that with neutral running shoes, ankle plantarflexion moment was higher compared to lightweight foam and AFT. There was less rearfoot eversion movement in the neutral shoe compared to lightweight foam and AFT. 

Cadence was lower while running in AFT shoes  compared to neutral or lightweight foam shoes. This is relevant since a longer running stride has been linked (in earlier studies) to BSI in the lower limbs.

Rearfoot eversion velocity (the speed at which your foot rolls down and inwards), or pronation was higher in the lightweight foam shoe compared with both neutral and AFT shoes. There was no significant difference in this between the neutral and AFT shoe.

The authors concluded that there were increases in several biomechanical variables associated with BSI  while running in AFT shoes. Although these changes were small, they tend to accumulate and can contribute to increased forces on bones in the lower limbs.  

The authors suggest that rotating running shoes and gradually using AFT to adapt to the differences may help reduce potential injury risk while optimizing running performance.

Reference

Bruneau MM, Gaudette LW, Sirls E et al (2026). Biomechanics Associated Withe Bone Stress Injuries While Using Advanced Footwear Technology In Elite Distance Runners. PM & R. 18(2): S143-150. DOI: 10.1002/pmrj.70153

Repeat The Same Training?

I started keeping a handwritten training log (pictured below) after I started running at 13. Back then there were no apps to keep such records for you. I would record how far I ran, time taken, how I felt, what shoes I used, etc. 

I found it useful so I could look back on what training I did when taking part in a similar event. Say my key interval workout for a 1500m track race that I had won previously was 8x200m with 30 seconds rest. I would replicate those sessions along with deciding if I could handle more. Back then, I was a teenager and was able to run personal bests in all my events every year.

I assume that when I responded well to a training program once, I'd respond similarly or better the next time. However, a recent study suggested otherwise.

A group of researchers had subjects do the same 8 week endurance training program twice, but separated by a period of detraining that had to return to baseline. 42 out of the 53 recruited completed the study.

Each 8 week period had 24 supervised 45 minute interval cycling sessions at moderate to maximal intensity. Identical training instructions were applied such that the same training program was repeatedly prescribed to the same individuals. Exercise intensity was individually prescribed relative to performance and adjusted every second week to mainatin a comparable training stimulus across periods.

Results show very poor reproducibility of adaptation. One athlete increased VO2 max by about 600mL min⁻¹ after the first training period. However, there was no improvement at all after the second training period. Yes you read correctly, zero improvement.

Same athlete, same program, but very different outcome. I asked a few coaches whom I treat if this was similar to the athletes they coach. They told me they see it all the time. Training response varies.

The training may be the same but the variations in external factors such as sleep, diet, work stress, travel and illness contributes to the variability in individual training adaptations.

That's what the researchers concluded too. The substantial within-individual fluctuations were largely consistent between training periods and they suggest that this  within-individual fluctuations does not reliably reflect their capacity to adapt to the same training stimulus in the future.

So low stress plus good training leads to adaptation while high stress plus the same training may lead to very different outcomes.

Take away message? Do not assume that because a program worked once, it will work the same way the next time. Monitor the state of your own life stresses and modify accordingly.

Reference

OddenIV, Hamarsland H, Odden TU et al (2026). Limited Reproducibility Of Individual Physiological Adaptations To Repeated Endurance Exercise Training. J App Phy. DOI: 10.1152/japplphysiol.00154.2026

Can You Trust AI With Nutritional And Athletic Performance Advice?

Picture from Sixminutemile.com

I was reading about how 2024 Olympic road race cycling winner Kristen Faulkner built her own artificial intelligence (AI) model to analyse 9 years of her own performance data to help her uncover what's missing from women's sports science. It allowed her to have data that helps explain not just what happened but why.

Faulkner said she coded to build the AI technology that can learn from data, spot patterns and make decisions. These are skills that we usually associate with human intelligence. 

AI is already in our everyday lives. We get Google Maps directing our commute, Spotify suggesting songs on your playlist and hit ChatGPT with any question we might have.

Many people use AI for everyday health, exercise and medical queries. Are these AI driven chatbots reliable and accurate? Our patients already use AI to self diagnose their pain and injuries. Some studies show chatbots are largely accurate, while others reported frequent errors and even a risk for transmitting inaccurate information.

The following research investigated 5 popular AI driven chatbots to evaluate their responses to everyday health and medical queries across 5 categories: cancer, vacines, stem cells, nutrition and athletic performance. Both open ended and closed ended questions were used.

Gemini, Meta AI, DeepSeek, ChatGPT and Grok were the 5 chatbots used. They were each presented with 50 prompts across the 5 topics mentioned above. The researchers used an adversarial framework to strain models towards misinformation or contraindicated advice.

An adversarial framework refers to a system, process or analytical model structured around opposition, competition or conflict. This is a cybersecurity approach used to test the vulnerabilities of AI systems.

Responses were then independently rated by 2 domain experts as non-problematic, somewhat problematic or highly problematic. Citations were assessed for authenticity and completeness while readability evaluated using the Flesch Reading Ease score (100 point scale with higher scores being easier to read).

Results showed that nearly half of ALL responses (49.6 percent) were problematic, 30 percent somewhat and 19.6 percent highly problematic. Nutrition and athletic performance topics had the weakest performance and Grok generated significantly more highly problematic responses than expected.

Reference quality was poor across all chatbots. The median completeness score was 40 percent. No chatbot came up with a fully accurate reference list. Misleading, unreliable or fabricated citations were common. So please be careful if you use them.

All the 5 chatbots produced responses that were rated "difficult" on the Flesch Reading Ease scale, equivalent to university-level reading. Chatbots answered consistently with confidence regardless of accuracy, while rarely declined to respond (2 refusals to answer across 250 total responses).

The researchers concluded that continued deployment of AI chatbots without public education and regulatory oversight risk amplifying health misinformation. Especially in the field of nutrition and athletic performance. They also suggested that public education, professional training and regulatory oversight to ensure that generative AI support rather than replace professionals.

My suggestion when searching for health information is to treat these AI chatbots with a good amount of skepticisim and to verify information with qualified professionals or peer-reviewed sources. There will be some benefit seeking ideas and initial information from a chatbot, but beyond that you will need a real human expert.

Reference

Tikker NB, Marcon AR, Zenone M et al (2026). Generative Artifical Intelligence-Driven Chatbots And Medical Misinformation: An Accuracy, Referencing And Readability Audit. BMJ Open. 16(4): e112695. DOI: 10.1136/bmjopen-2025-112695.